#!/usr/bin/env python3
# Implements: REQ-1
"""Validate that a PR has a spec file with required sections and acceptance criteria.

Spec-driven development gate. Runs in CI before expensive jobs.
Used by grm, infra, sso-bridge, and devx itself.

Validates:
1. A spec file exists at ``docs/specs/<TASK-ID>.md`` (TASK-ID extracted from branch).
2. The spec contains required sections: Problem, Approach, Test Plan, Deploy Plan, Rollback Plan.
3. The spec contains REQ-ID lines (``REQ-N: <description>``).
4. The spec contains an Acceptance Criteria checklist with at least one item.
5. All acceptance criteria checkboxes are checked (``- [x]``).

Usage:
    python -m devx.ci.validate_spec --branch OBL-INFRA-531-fix-foo

In CI, also pass ``--github-output`` to set ``spec-valid`` and ``spec-path``
for downstream steps.
"""

from __future__ import annotations

import re
from pathlib import Path

import click
from dotenv import load_dotenv

from devx.ci._shared import extract_task_id, write_github_output
from devx.i18n import _

load_dotenv()

REQUIRED_SECTIONS = [
    "## Problem",
    "## Approach",
    "## Test Plan",
    "## Deploy Plan",
    "## Rollback Plan",
    "## Acceptance Criteria",
]

REQ_ID_RE = re.compile(r"^REQ-\d+:\s+.+", re.MULTILINE)
AC_CHECKED_RE = re.compile(r"^\s*- \[x\]\s+.+", re.MULTILINE)
AC_UNCHECKED_RE = re.compile(r"^\s*- \[ \]\s+.+", re.MULTILINE)


def find_spec_file(task_id: str, specs_dir: str = "docs/specs") -> Path | None:
    """Find the spec file for the given task ID.

    Looks for ``docs/specs/<TASK-ID>.md`` (case-insensitive filename).
    Returns the Path if found, None otherwise.
    """
    base = Path(specs_dir)
    if not base.is_dir():
        return None
    # Exact match (case-insensitive)
    for p in base.glob("*.md"):
        if p.stem.upper() == task_id.upper():
            return p
    return None


def validate_spec_content(content: str) -> list[str]:
    """Validate spec content and return a list of error messages.

    Returns an empty list if the spec is valid.
    """
    errors: list[str] = []

    # Check required sections
    for section in REQUIRED_SECTIONS:
        if section not in content:
            errors.append(_("Missing required section: {section}", section=section))

    # Check for at least one REQ-ID
    req_ids = REQ_ID_RE.findall(content)
    if not req_ids:
        errors.append(_("No REQ-ID lines found. Each requirement must be labeled (e.g., 'REQ-1: <description>')."))

    # Check acceptance criteria has at least one item
    checked = AC_CHECKED_RE.findall(content)
    unchecked = AC_UNCHECKED_RE.findall(content)
    if not checked and not unchecked:
        errors.append(_("Acceptance Criteria section has no checklist items. Add at least one '- [ ] item'."))
    elif unchecked:
        errors.append(
            _(
                "Acceptance Criteria has {count} unchecked item(s). All AC items must be checked (- [x]) before merge.",
                count=len(unchecked),
            )
        )

    return errors


@click.command()
@click.option("--branch", required=True, help=_("Branch name (e.g., OBL-INFRA-531-fix-foo)"))
@click.option("--specs-dir", default="docs/specs", help=_("Directory containing spec files"))
@click.option(
    "--github-output",
    "github_output",
    is_flag=True,
    default=False,
    help=_("Write results to $GITHUB_OUTPUT"),
)
@click.option("--allow-missing", is_flag=True, default=False, help=_("Allow missing spec (warn only, don't fail)"))
def cli(branch: str, specs_dir: str, github_output: bool, allow_missing: bool) -> None:
    """Validate that a spec file exists and has required content."""
    task_id = extract_task_id(branch)
    if not task_id:
        msg = _("No task ID found in branch name '{branch}'. Expected format: <PREFIX>-N-description.", branch=branch)
        if allow_missing:
            click.echo(f"WARNING: {msg}")
            if github_output:
                write_github_output("spec-valid", "false")
                write_github_output("spec-path", "")
            return
        raise click.ClickException(msg)

    spec_path = find_spec_file(task_id, specs_dir)
    if spec_path is None:
        msg = _(
            "No spec file found for task {task_id} in {dir}/. Expected: {dir}/{task_id}.md",
            task_id=task_id,
            dir=specs_dir,
        )
        if allow_missing:
            click.echo(f"WARNING: {msg}")
            if github_output:
                write_github_output("spec-valid", "false")
                write_github_output("spec-path", "")
            return
        raise click.ClickException(msg)

    content = spec_path.read_text(encoding="utf-8")
    errors = validate_spec_content(content)

    if github_output:
        write_github_output("spec-valid", "true" if not errors else "false")
        write_github_output("spec-path", str(spec_path))

    if errors:
        click.echo("", err=True)
        click.echo("=" * 60, err=True)
        click.echo(f"Spec validation FAILED for {spec_path}:", err=True)
        click.echo("=" * 60, err=True)
        for e in errors:
            click.echo(f"  - {e}", err=True)
        raise click.ClickException(_("Spec validation failed."))

    click.echo(_("[spec-check] Spec validated: {path}", path=spec_path))


if __name__ == "__main__":  # pragma: no cover
    cli()